The present invention is directed generally to liquid conductivity monitoring systems, and more particularly to an improved monitoring system for a reverse osmosis liquid purification system.
Reverse osmosis systems have come into wide use for removing impurities in water. In such systems, a flow of water is caused to pass through a semi-permeable membrane. Dissolved impurities, including ionic particles, are trapped by the membrane, so that water downstream of the membrane is free of the impurities and has a lower ion concentration than water upstream of the membrane.
To preclude the undetected presence of impurities in the output product, such as might occur upon rupture or deterioriation of the membrane of a reverse osmosis system, it is desirable that the system be continuously monitored and an unambiguous signal be given to the operation upon malfunction of the system. Since the conductivity of the aqueous solution undergoing purification is approximately proportional to dissolved ion concentration, which is in turn dependent on the performance of the reverse osmosis filter, an indication of system performance can be had by comparing water conductivity upstream of the filter with water conductivity downstream of the filter.
Various monitoring systems have been proposed using water conductivity including those shown in U.S. Pat. Nos. 4,587,518, 4,528,093, 4,498,982, 4,496,906 and 4,028,666. U.S. Pat. No. 4,496,906, which is a prior patent of the present inventor, in addition describes a novel two light indicator system for indicating water conductivity above or below a predetermined threshold level at a single monitoring location. The present invention is directed to an improved monitoring system for a reverse osmosis liquid processing system which is economical and reliable, and provides the user with an unambiguous indication of satisfactory system operation.
Accordingly, it is a general object of the present invention to provide a new and improved monitoring system for a liquid purification system of the type having an inline membrane.
It is a more specific object of the present invention to provide a monitoring system for a liquid purification system which is simple and reliable in construction, and which provides an unambiguous indication of unsatisfactory system operation.